Russia has said it will expel a US diplomat accused of working as a spy after he was arrested while trying to recruit a Russian agent for the CIA, in an elaborate raid that revealed the American was carrying a bizarre arsenal of suspected spying equipment.

Ryan Fogle, the third secretary at the US embassy in Moscow, was paraded in footage aired on state-run television after being detained late on Monday night by officers from the Federal Security Service (FSB), a successor to the Soviet-era KGB.

He stands accused of being a CIA spy and was declared persona non grata by the foreign ministry on Tuesday .

"A classic spy arsenal was discovered, as well as a large sum of money that doesn't just expose a foreign agent caught red-handed, but also raises serious questions for the American side," the ministry said. "Such provocative actions in the spirit of the cold war in no way help to strengthen mutual trust."

Fogle was said to be carrying two wigs, three pairs of glasses, a compass and map of Moscow, as well as a knife, lighter, stacks of €500 notes and his US embassy ID.

Russia Today, an English-language TV channel run by the Kremlin, also revealed the contents of an alleged letter addressed to the Russian recruit.

It begins: "Dear friend, This is a down-payment from someone who is very impressed with your professionalism and who would greatly appreciate your co-operation in the future." It goes on to offer $100,000 "to discuss your experience, expertise and co-operation" as well as $1m "for long-term co-operation".

It then instructs the recruit on how to open a Gmail account, before signing off with "your friends". The letter, wigs, and immediate release of footage of the raid to state-run television like Russia Today elicited widespread confusion.

The scandal comes at an awkward time in US-Russia relations. On one hand, the Russian president, Vladimir Putin, has repeatedly blamed the US for fomenting discontent with his government, with officials going so far as to accuse the state department of funding opposition protesters. On the other, Moscow and Washington have been seeking to strengthen co-operation after the attack on the Boston marathon, suspected to have been carried out by two men with roots in Russia's troubled North Caucasus region.

It also comes less than a week after John Kerry, the US secretary of state, visited Moscow to help end the war in Syria. He was accompanied by Robert Mueller, the FBI director, who held a rare meeting with his Russian counterpart. In Washington, a state department spokesman said: "We can confirm that an officer at our US embassy in Moscow was briefly detained and was released." They declined to comment further. The foreign ministry summoned the US ambassador, Michael McFaul, for a meeting on Wednesday.

In the video released by the FSB, a plain-clothed officer, his face distorted for the camera, is shown peeling a grey cap and blond wig off Fogle's head, before marching him to a car. Fogle is then shown seated, stone-faced, inside an FSB questioning site with three unidentified Americans, as a Russian official accuses him of trying to recruit a Russian intelligence officer involved in anti-terrorism efforts in the North Caucasus.

"At first, we didn't believe this could happen, because you very well know that lately the FSB has been actively helping the investigation of the Boston bombs," the official says. He goes on to lecture the group about US-Russia relations, and aims to increase co-operation following telephone talks between Putin and US President Barack Obama.

"Understandings were reached about co-operation," the Russian says. "And on this background, when relations are being strengthened between the countries, an American diplomat commits a government crime against the Russian Federation."

In a rare statement, the FSB said Fogle's alleged attempt to recruit a Russian agent was not unique. "Lately, American intelligence has made multiple attempts to recruit employees of Russian law enforcement organs and special agencies, which have been detected and monitored by FSB counter-intelligence," it said.

The US has been at pains to reconstruct the six months that Tamerlan Tsarnaev, accused of carrying out the Boston bombing and subsequently killed in a shootout with police, spent in Dagestan, a volatile republic in Russia's south in 2012.

In 2011, Russia had warned the FBI about Tsarnaev but, according to US officials cited by the Wall Street Journal, refused to respond to requests for information.

The bizarre details of the raid to capture Fogle recalled the "spy rock" scandal of 2006, when Russia said it had caught British spies "red-handed" using a fake rock fitted able to transmit classified data. Britain initially laughed off the scandal as absurd, but early last year, Jonathan Powell, former chief of staff to then prime minister Tony Blair, admitted it was true. He called the spy rock "embarassing". "They had us bang to rights."

The Fogle scandal comes three years after the US broke up a sleeper cell of 10 Russian spies and expelled them via a dramatic swap at Vienna airport. The ring's most famous spy, Anna Chapman, has gone on to have a successful career as a TV host and Kremlin cheerleader at home.

It was unclear whether the US would respond with a tit-for-tat expulsion, coming as the scandal does amid concerted US, UK and Israeli efforts to convince Russia to drop support for Bashar al-Assad. Last week, Kerry and Sergei Lavrov, the Russian foreign minister, agreed to call a conference aimed at helping end the war.

Putin was meeting Benjamin Netanyahu, the Israeli prime minister, in the southern city of Sochi when news of the spy scandal broke.

Russian officials tried to downplay the scandal, including Alexey Pushkov, head of the Duma's international affairs committee and one of government's loudest US critics. "The spy scandal around the American diplomat will be, I think, fleeting," Pushkov tweeted. "And it won't bother the Lavrov-Kerry negotiations. But it won't help the atmosphere."